Crankshaft speed plot for misfire detection

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samjesse
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Joined: Fri Feb 08, 2013 4:45 pm

Crankshaft speed plot for misfire detection

Post by samjesse »

Hi
Is there a function where by the speed of the crank shaft can be displayed, I need to see the speed as it varies to locate the cylinder causing a misfire which did not set a code?
Also to plote the cylinders according to their fireing order as per this article
https://www.mechanic.com.au/news/detect ... >Detecting Misfires That Don’t Set Trouble Codes
Any help is greatly appreciated.

Steve Smith
Pico Staff Member
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Posts: 1581
Joined: Sun Aug 25, 2013 7:22 am

Re: Crankshaft speed plot for misfire detection

Post by Steve Smith »

Hello and thank you for the post

The following links will help with graphing rpm and more importantly the acceleration and deceleration of the crankshaft topic11511.html

The procedure has changed a little with PicoScope 7 and improvements have been made to the functionally too

The following link here to PS7 Math channels will help viewtopic.php?p=100244#p100244 which includes a short video too. The video covers the creation of a -duty math channel but the procedure is near identical for “crank maths”

The image below will help
Image 1A
Image 1A
Once you have your crank math channel displayed you can then add a synchronization signal to either petrol ignition or diesel injection event and use the firing order to find the offending cylinder.

PicoScope does have phase rulers to help with the identification of the 4-stroke cycle and rotational measurements which you can view here viewtopic.php?p=99874#p99874

For a cylinder plot chart, PicoScope does not include such a feature but there are numerous 3rd party overlay charts you can use, one of which is https://www.microsoft.com/en-gb/p/press ... verviewtab

I hope this helps, take care…..Steve

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